|Publication number||US7954995 B2|
|Application number||US 12/632,071|
|Publication date||Jun 7, 2011|
|Filing date||Dec 7, 2009|
|Priority date||Aug 8, 2006|
|Also published as||US7651267, US20080036590, US20100080263|
|Publication number||12632071, 632071, US 7954995 B2, US 7954995B2, US-B2-7954995, US7954995 B2, US7954995B2|
|Inventors||Philip Gonzales, Ronald Elder|
|Original Assignee||Ford Global Technologies, Llc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (30), Classifications (15), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of U.S. application Ser. No. 11/463,057 filed 8 Aug. 2006, now U.S. Pat. No. 7,651,267, which is hereby incorporated herein by reference.
1. Field of the Invention
The present invention relates to a sensor arrangement and a method for using a sensor arrangement to determine a value of at least one property of a selected object.
2. Background Art
Determining the value of a property of a device—e.g., the temperature of a heat producing device—can require one or more sensors connected to a receiving unit, such as a control module, often with a complex wiring distribution system. In addition to carrying the signal from the sensors, wires may be required for transmission of power to active electronic elements in a sensor circuit to facilitate their operation.
When it is desired to measure more than one property, the number of sensors, and the complexity of the information distribution system may increase significantly. For example, high voltage battery systems in hybrid electric vehicles and fuel cell vehicles require voltage and temperature sensing to determine the operating state of the battery systems to properly control the powertrain and other systems of the vehicle. Conventional systems relay the voltage and temperature information to one or more control modules in the vehicle. The information is transferred via a wiring distribution system that uses an undesirable amount of package space, requires special shielding from heat and electromagnetic interference, requires special assembly processes, and has life and reliability concerns. Sensing systems that do not require wires to transfer information—e.g., infrared system—require a line of sight between the sensors and the unit receiving the sensed information. Such line-of-sight systems are not practical for most vehicle applications.
Therefore, a need exists for a sensor arrangement that can provide information about the properties of devices and systems without using a complex wiring system to transfer the information between the sensors and a receiving unit. In addition, there is a need for a sensor arrangement that does not include active electronic components that require a source of power for their operation.
Accordingly, the present invention provides a sensor arrangement that is adaptable for use with one or more sensors configured to transmit information wirelessly to a receiving unit without requiring a line of sight between the sensors and the receiving unit.
The invention also provides a sensor arrangement that can be used to determine the values of different properties, such as temperature and voltage, of one or more selected objects. The sensor arrangement uses passive devices that do not require a power source for their operation.
In addition to including one or more sensors in the sensor arrangement of the present invention, embodiments may include identification circuits so that the sensors and the respective objects they are working on can be easily identified. The identification circuit can be integrated into the sensor arrangement, such that identification information is also transmitted wirelessly, without the need for an external power source, such as a battery.
The invention further provides a sensor arrangement for determining a value of at least one property of a selected object. The sensor arrangement includes a magnetostrictive element configured to output magnetic signals in response to an alternating magnetic field. The sensor arrangement also includes a first sensor configured to sense a value of a property of the selected object, and to provide an electrical resistance that varies in response to variations in the sensed value. The first sensor cooperates with the magnetostrictive element to vary the frequency of the signals output by the magnetostrictive element based on variations of the electrical resistance provided by the first sensor.
The invention also provides a sensor arrangement that includes a passive transducer configured to output mechanical oscillations at a frequency in response to a magnetic field. The mechanical oscillations generate corresponding magnetic output signals that can be received by a control module remotely located from the transducer. A first sensor, such as described above, cooperates with the transducer, such that the frequency of the output signals generated by the transducer is at least in part dictated by the electrical resistance provided by the first sensor.
The invention further provides a method for determining a value of at least one property of at least one selected object using a sensor arrangement that includes a passive transducer and a first sensor, such as described above. The method includes sensing a value of a first property of the selected object, sending a magnetic field to the transducer, receiving the output signals generated by the transducer, and determining the sensed value of the first property using the output signals received. This determination includes correlating the frequency of the output signals received with the resistance of the first sensor, and correlating the resistance of the first sensor with the sensed value.
In particular embodiments of the present invention, the sensor arrangement can include an acousto-magnetic system and a sensor providing a variable resistance, such as a thermistor. Acousto-magnetic systems are well known in the art, and are frequently used in electronic article surveillance (EAS) systems. One such device is described in U.S. Pat. No. 5,495,230 issued to Lian on Feb. 27, 1996, which is hereby incorporated herein by reference.
Embodiments of the present invention using an acousto-magnetic system may use a magnetostrictive element such as those found in EAS systems. The magnetostrictive element is made from one or more ferromagnetic metals, such as iron or nickel. The element can be fashioned in the shape of a very thin coil of the type frequently found in the anti-theft devices on consumer articles. In the presence of a magnetic field, the magnetostrictive element deforms, and where the magnetic field is alternating, the magnetostrictive element produces mechanical oscillations. Because the element is magnetic, these oscillations also produce a magnetic output signal that can be picked up by a receiver, which can be configured to determine the frequency of the output signals generated by the element.
In embodiments of the present invention, a sensor, such as a thermistor, is connected to the magnetostrictive element such that the thermistor provides a resistance to the oscillations of the element. The resistance provided by the thermistor changes with the temperature of the object to which the thermistor is attached. Thus, the thermistor provides a resistance to the magnetostrictive element that varies with variations in the temperature of the object being examined.
The frequency of the signal output by the magnetostrictive element is dependent on the resistance provided by the thermistor. Thus, as the temperature of the object changes, the resistance provided by the thermistor changes, and the frequency of the signals output by the magnetostrictive element changes. In this way, the frequency of the output signal generated by the magnetostrictive element is indicative of the temperature of the object. When the receiver picks up the output signal from the magnetostrictive element, it can itself process the information, or send it to some other control unit to process and interpret the signal. This provides a robust system for measuring the temperature of an object remotely, without the use of wires, and without requiring a line of sight between the sensor and the receiver. In addition, a thermistor and the magnetostrictive element can be provided in a very small package, thereby providing a sensor arrangement that is lightweight, and has the ability to be positioned directly on a particular object. This is in contrast to measuring a proximity temperature that provides only an estimate of the temperature of the actual object.
In addition to a thermistor, or instead of a thermistor, other sensors can be combined with a passive transducer, such as a magnetostrictive element in accordance with embodiments of the present invention. For example, an integrated circuit can be configured to measure voltage, such that a variation in the voltage being measured causes a variation in the resistance of the voltage circuit. Such a circuit can be combined with a magnetostrictive element in a similar fashion to the thermistor example described above. In an application such as a high voltage battery in a hybrid or a fuel cell vehicle, many such sensing elements can be used to provide information about the temperature and/or voltage of different battery modules within the battery pack. For example, a high voltage battery system may include 200-300 battery cells, which can be conveniently linked in battery modules containing 4-16 cells. By using a sensor arrangement in accordance with the present invention, thermistor circuits and voltage circuits can be combined with passive transducers and placed on some predetermined number of the battery cells or battery modules. In such an application, it may be convenient to know the location of each of these sensor arrangements. Therefore, the present invention also provides a mechanism for identifying the particular sensor unit—i.e., the sensor/transducer combination—that is providing the output signals.
In some embodiments of the present invention, an identification circuit, for example in the form of a semiconductor, is attached to a magnetostrictive element in a fashion similar to the sensors described above. Unlike the thermistor, or other sensor that provides a resistance that varies in accordance with the value of the property being measured, the identification circuit can be provided with a single resistance, and each identification circuit used in a particular application can be provided with a different, generally constant resistance. In addition, a sensor arrangement in accordance with the present invention can include control circuitry, for example, integrated into the identification circuit, that allows the sensors to be enabled and disabled as desired. In this way, the identification circuit can disable all of the sensors it is associated with, so that the only resistance that influences the output signal of the magnetostrictive element is the resistance of the identification circuit itself. This results in a different frequency for the output signals received from each of the different sensor units. This allows each of the sensor units to be identified. When the sensor units are used, for example, in a high voltage battery system for a hybrid vehicle, identification of the sensor units allows for identification of the battery modules.
In one embodiment of the present invention, the sensor arrangement includes a number of sensor units, each of which has a magnetostrictive element, an identification circuit, a thermistor, and a voltage sensor. The identification circuit provides a generally constant reference resistance to the magnetostrictive element, and also includes control circuitry to selectively enable and disable the thermistor and the voltage sensor. An antenna is connected to a battery control module (BCM) to output the magnetic field to each of the sensor units. The BCM can be configured to generate the magnetic field, and specifically, provide the input to the sensor units in the form of a pulsed magnetic field. This allows the magnetostrictive elements to be excited while the pulse is on, and to provide an output signal back to the antenna when the pulse is off. In addition to providing the magnetic field to the magnetostrictive elements, the antenna also receives the output signals from each of the elements, such that the BCM acts as both a transmitter and a receiver.
The control circuitry integrated into the identification circuit is configured such that when the vehicle is first started—i.e., when the vehicle is in a key-on state—each of the sensors associated with a particular identification circuit will be disabled. The BCM then provides a magnetic field to each of the sensor units on the battery modules. The frequency of the output signals from each of the magnetostrictive elements will now be affected by the identification circuit, but not by any of the thermistors or voltage sensors. When the output signals from the magnetostrictive elements are received by the BCM, each of the sensor units, and hence the battery modules, can be identified.
The control circuitry integrated into the identification circuits is also configured such that after the vehicle leaves the key-on state, and is in an operating state, the thermistors and the voltage sensors will be alternately enabled and disabled, such that only one of these devices in each sensor unit is enabled at one time. For example, when the BCM outputs a magnetic field to the sensor units the first time the vehicle leaves the key-on state, each of the thermistors may be disabled by the control circuitry in a respective identification circuit, so that the voltage of each of the battery modules can be determined. The next time the BCM outputs the magnetic field to the sensor units, the control circuitry can disable each of the voltage sensors, and enable each of the thermistors, such that the temperature of each of the battery modules can be determined. The alternating of the enabling and disabling of the sensors can be controlled, for example, through the use of a clock circuit in the control circuitry. In this way, each of the thermistors remains enabled for a predetermined time, and then is disabled. Similarly, each of the voltage sensors remains enabled for a certain period of time, and then is disabled.
In addition to the information sensed directly by each of the sensors, the information provided by the sensor arrangement of the present invention can be combined with other information about vehicle systems to provide even more useful data for controlling the vehicle and its systems. For example, as the voltage of each of the battery modules is determined, the receipt of the information can be time stamped so that it can be correlated with battery current measurements that are also time stamped. In this way, a determined voltage and a determined current of the battery, each measured at the same time, can be used to determine the state of charge (SOC) of the battery module at that time. This information is very useful, in that many of the controls of hybrid electric vehicles are based on battery SOC. Moreover, because the SOC can be determined for individual battery modules, and because each of these battery modules can be identified, it is possible to provide targeted maintenance to the battery so that only certain battery modules are repaired or replaced, instead of replacing the entire battery system. The information received by the BCM can be communicated to other onboard controllers, such as a vehicle system controller (VSC) and/or a powertrain control module (PCM). In addition, output from the BCM can be connected to operator indicators, such as those found in an operator information display in an instrument panel.
Different magnetostrictive elements have different resonant frequencies that may be affected by the size and shape of the element. Therefore, the packaging considerations of the particular application, as well as the desired frequency of the magnetostrictive element, may need to be taken into account when determining the size of the sensor arrangement. As shown in
As shown in
Shortly after the PWM signal is stopped, the magnetostrictive element 12 continues to vibrate, thereby outputting magnetic signals back to the control module 22 at some frequency—i.e., the magnetostrictive element 12 “rings back”. The control module 22 is configured to determine the frequency of the signal it receives, and correlate that frequency with the resistance provided by the thermistor 18. The resistance provided by the thermistor 18 can then be correlated to the temperature being sensed, and thus, the temperature of the object 20 at the location of the sensor unit 11 is determined. The control module 22 is connected to an output interface 26 so that the information picked up from the sensor unit 11 can be used by other controllers and other systems, for example, throughout a vehicle.
In addition to being connected to the magnetostrictive element 32, the voltage sensor 36 is also connected to two leads 38, 40 which respectively terminate at contacts 42, 44. The contacts 42, 44 can be directly attached to the positive and negative terminals on a battery cell, a battery module, or an entire battery pack. Similar to the function of the thermistor 34, the voltage sensor 36 provides a resistance to the magnetostrictive element 32 that varies with variations in the value of a particular sensed property—i.e., the voltage of the selected battery. In this way, the signals output by the magnetostrictive element 32 will have different frequencies, depending on the voltage sensed by the sensor 36.
In addition to the sensors 34, 36, the sensor unit 30 also includes an identification circuit 46. The identification circuit 46 provides a generally constant resistance to the magnetostrictive element 32, thereby providing the sensor arrangement 28 with a number of advantageous features. For example, because the resistance of the identification circuit 46 is generally constant and is known, its influence on the frequency of the signals output by the magnetostrictive element 32 can be easily accounted for if one or both of the sensor 34, 36 are enabled. In addition, where a sensor arrangement, such as the sensor arrangement 28, includes more than one sensor unit, such as the sensor unit 30, each identification circuit on a respective sensor unit can be configured with a different resistance. In this way, signals received from multiple sensor units can be identified, thereby identifying the object to which the sensor unit is attached.
In addition, to providing an easy and effective means for identifying the sensor unit, the identification circuit 46 is also configured with control circuitry that can selectively enable and disable the sensors 34, 36. As described above, this provides a mechanism for easily identifying a particular property—e.g., a temperature or a voltage—of an object such as a battery.
Surrounding the battery system 48, and therefore each of the sensor units 52-68, is an antenna 70, which is attached to a BCM 72. Just like the control module 22 described in
The BCM 72 is specifically configured to output a PWM signal, illustrated as a square wave signal 74 in
By way of example, a VSC may provide information to the BCM indicating that the vehicle is in a key-on state, or that it is in a normal operation state. This information can be used to determine whether the control circuitry in the identification circuits of the sensor units 52-68 should enable or disable one or more of their associated sensors, such as the sensors 34, 36. As described above, this provides an easy and effective mechanism for independently determining the sensed values of the battery properties, such as the voltage and temperature.
Although the antenna 70, in the embodiment shown in
While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.
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|U.S. Classification||374/176, 374/187, 374/183, 374/163|
|International Classification||G01K7/00, G01B1/00, G01R3/00|
|Cooperative Classification||H04Q2209/10, H04Q2209/40, H04Q2209/30, G01K1/024, H04Q9/00, G01K2215/00|
|European Classification||H04Q9/00, G01K1/02C|